Breast cancer is the second leading cause of death in women. The spread of cancer from the breast to the lymph nodes is a significant factor in determining breast cancer survival. Currently, surgical procedures are performed to determine lymph node involvement. Full axillary lymph node dissection has a high morbidity associated with the procedure. While sentinel lymphadenectomy avoids a full axillary dissection in clinically negative axilla in untreated patients, it has been reported to have a false negative rate of less than 10%. Others have reported higher false negative rates after neoadjuvant chemotherapy. For those reasons, there is considerable interest in non-invasive methods that may allow staging of the axilla.